Make sure configuration is saved to storage device

Config file is written to a temp file and then it is renamed to the
original config file. However, it is possible that the rename operation
will be commited to storage while file data will be still in cache
causing original config file to be empty or partially written in case of
a system reboot without a clean shutdown. Make this less likely to occur
by forcing the data to be written to the storage device before renaming
the file.

Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>

diff --git a/src/utils/os.h b/src/utils/os.h
index 2c24631bf46e121950c4df1fee2c1a21740f5255..9e496fb6597830fc5d5146065b4c5ca5b23984c6 100644 (file)
--- a/src/utils/os.h
+++ b/src/utils/os.h
@@ -246,6 +246,13 @@ char * os_readfile(const char *name, size_t *len);
  */
 int os_file_exists(const char *fname);
 
+/**
+ * os_fdatasync - Sync a file's (for a given stream) state with storage device
+ * @stream: the stream to be flushed
+ * Returns: 0 if the operation succeeded or -1 on failure
+ */
+int os_fdatasync(FILE *stream);
+
 /**
  * os_zalloc - Allocate and zero memory
  * @size: Number of bytes to allocate

diff --git a/src/utils/os_internal.c b/src/utils/os_internal.c
index 77733ad916cd0026b0d08a9040617698154e0e6c..ed6eb3c6b67704679883ecb0d5d2034900b7f492 100644 (file)
--- a/src/utils/os_internal.c
+++ b/src/utils/os_internal.c
@@ -243,6 +243,12 @@ char * os_readfile(const char *name, size_t *len)
 }
 
 
+int os_fdatasync(FILE *stream)
+{
+       return 0;
+}
+
+
 void * os_zalloc(size_t size)
 {
        void *n = os_malloc(size);

diff --git a/src/utils/os_none.c b/src/utils/os_none.c
index 83fe025167b6f9cd60d1e79525bc222a63651429..0c3214d32ce50f2b9d77b6d3b9fb43b0e45190cb 100644 (file)
--- a/src/utils/os_none.c
+++ b/src/utils/os_none.c
@@ -102,6 +102,12 @@ char * os_readfile(const char *name, size_t *len)
 }
 
 
+int os_fdatasync(FILE *stream)
+{
+       return 0;
+}
+
+
 void * os_zalloc(size_t size)
 {
        return NULL;

diff --git a/src/utils/os_unix.c b/src/utils/os_unix.c
index 089b880bd3f46890d2b0a7e82253082e46d4e71f..4754dd7a14a0a721cd3b0549180019be4372a8db 100644 (file)
--- a/src/utils/os_unix.c
+++ b/src/utils/os_unix.c
@@ -418,6 +418,14 @@ int os_file_exists(const char *fname)
 }
 
 
+int os_fdatasync(FILE *stream)
+{
+       if (!fflush(stream))
+               return fdatasync(fileno(stream));
+       return -1;
+}
+
+
 #ifndef WPA_TRACE
 void * os_zalloc(size_t size)
 {

diff --git a/src/utils/os_win32.c b/src/utils/os_win32.c
index 296ea13f153b4e5df54b7263d781f4f6648b21a8..dea27b9f2ad846c709f6074b4ff0985b0970aade 100644 (file)
--- a/src/utils/os_win32.c
+++ b/src/utils/os_win32.c
@@ -216,6 +216,24 @@ char * os_readfile(const char *name, size_t *len)
 }
 
 
+int os_fdatasync(FILE *stream)
+{
+       HANDLE h;
+
+       if (stream == NULL)
+               return -1;
+
+       h = (HANDLE) _get_osfhandle(_fileno(stream));
+       if (h == INVALID_HANDLE_VALUE)
+               return -1;
+
+       if (!FlushFileBuffers(h))
+               return -1;
+
+       return 0;
+}
+
+
 void * os_zalloc(size_t size)
 {
        return calloc(1, size);

diff --git a/wpa_supplicant/config_file.c b/wpa_supplicant/config_file.c
index 2af187dd42844f8dc86147525899b6ac66de0608..fb438ea43e13f07b110b7004632f49e16f522a92 100644 (file)
--- a/wpa_supplicant/config_file.c
+++ b/wpa_supplicant/config_file.c
@@ -1361,6 +1361,8 @@ int wpa_config_write(const char *name, struct wpa_config *config)
        }
 #endif /* CONFIG_NO_CONFIG_BLOBS */
 
+       os_fdatasync(f);
+
        fclose(f);
 
        if (tmp_name) {